...use not registered font types?

procedure TForm1.FormCreate(Sender: TObject);
begin
  AddFontResource(PChar(ExtractFilePath(ParamStr(0) + 'YourFont.TTF')));
  SendMessage(HWND_BROADCAST, WM_FONTCHANGE, 0, 0);
end;


procedure TForm1.FormDestroy(Sender: TObject);
begin
  RemoveFontResource(PChar(ExtractFilePath(ParamStr(0) + 'YourFont.TTF')));
  SendMessage(HWND_BROADCAST, WM_FONTCHANGE, 0, 0);
end;